1. Field of the Invention
The present invention relates to a method of positioning a dental implant or surgical tool at a desired site. Various aspects of the present invention relate to a method of positioning a dental implant utilizing a dental model, preparing a surgical guide, using the surgical guide to perform an osteotomy and align a dental implant, and intra-oral placement of the dental implant. Various aspects of the present invention relate to a surgical guide for accurately determining a position for an implant and translating a position on a model to a site in a subject on which a procedure is to be performed.
2. Description of Related Art
Dental implants are an increasingly popular option for patients with missing teeth due to excessive decay, bone or gum damage, or accidents causing physical displacement and the like. Dental implants provide an attractive alternative to dentures because they look natural and require less maintenance. Implants further provide a stronger biting surface and allow patients to resume their normal diets.
In comparison to dentures, however, dental implant procedures involve costly and complex surgical work. More specifically, dental implant procedures generally involve the placement of a dental implant or abutment in the underlying jawbone as a foundation, and the subsequent attachment of a prosthetic to the implant above the gum line. Generally, a dental osteotomy must be performed to prepare the bone for placement of the implant. The implant is then inserted and fixed into the bone where it serves to hold the dental prosthetic. An important aspect of the implant plan is the accurate positioning of the implant in the bone.
The most difficult and skill-intensive part of the implant procedure is generally positioning of the drill to create the hole in the jawbone that will receive the implant. The hole must be formed at the precise desired location relative to adjacent teeth for a natural, attractive look and to reduce the risk of interference with the adjacent teeth. The hole must also be positioned in the proper location in the bone to ensure a solid base for the prosthetic. Inaccuracies in placing the hole can damage nearby vital structures such as nerves, blood vessels, sinus and neighboring teeth.
It is desirable to reduce the risk of mistakenly drilling in an incorrect position. Improper placement of the hole for the implant presents problems for the surgeon during placement of the implant in the bone. If the hole is not placed in the proper position in the jawbone, further drilling may be necessary. Even more troublesome, if bone has been mistakenly removed, new bone may have to be grafted or added to the site. Because the graft has to set and the tissue must heal, bone grafting generally requires an additional 3-6 months before a new attempt can be made. Positioning mistakes also require additional office visits by the patient, additional time to completion, and unnecessary discomfort. For these reasons, implant procedures typically require the expertise of specialized surgeons and usually are avoided by less experienced surgeons and general dentists.
Many tools and methods have been developed for increasing the accuracy, reliability, and ease with which a practitioner can perform the drilling operation. The most popular technique remains free-hand alignment. In the case of free-hand drilling, a surgeon draws upon his or her extensive experience to determine the proper trajectory and final location of the implant. Not only does this require a steady hand, but the surgeon must also make a judgment as to where the bone is located below the gum surface. Because the bone is masked under the gum tissue, and because it is difficult to fully inspect the site, the surgeon typically has great difficulty in determining the proper position in this initial step.
The flap method is the typical method for overcoming the problem of determining bone position below the gum line. The flap method involves physically cutting a flap of skin near the site and surveying the implant site to determine the position of the jawbone relative to the implant. This method increases the risk of infection and provides further discomfort for the patient.
Free-hand drilling also presents safety hazards and accuracy problems. Although the surgeon can initially determine where to drill, during the drilling procedure, the drill bit can “jump” or slip. The drill bit can also “walk” or move before the tip of the bit grabs or digs into the bone. Additionally, free-hand drilling requires the surgeon to act without a complete view of the mouth interior and implant site.
Model-based or lab-based methods allow improved positioning by allowing less invasive surveying of the implant site and advanced planning for the procedure. An exemplar of the prior art is U.S. Pat. No. 7,086,860 to Schuman et al. The Schuman method involves using tools to determine the size, angle, and position of the dental implant on a model cast. The cast is cut to determine the bone position. A graphic is then drawn on the model and tools are used to transfer the placement information of the graphic to the implant site. In the laboratory, the buccal-lingual (“BL”) volume of bone is derived from the subtraction of the tissue depth as measured in the mouth through bone sounding. If the anatomy is followed, an accurate reflection of the available bone volume for the implant placement may be determined. The mesial-distal (“MD”) positioning of the implant is derived from the transpositioning or translation of information from a radiograph onto the cast.
The above method has several limitations. The MD positioning in the lab is only an estimate and is not verifiable until transferred to the mouth. Also, this method usually only allows the surgeon to practice drilling on a model and does not assist with precisely transferring or mapping the determined drilling position from the model back to the implant site in the subject patient. Ultimately, the drilling procedure still requires a steady hand and drilling expertise. Another technique involves fashioning a drill guide from the model. Errors, however, still often occur when transferring the model positioning to the drill guide. Additionally, the drill guide does not allow for controlled adjustment.
U.S. Pat. No. 6,971,877 to Harter is directed to a dental tool formed of a stent and a bushing holder for guiding a drill bit. The stent is formed on a model and configured to fit a patient's jaw. The bushing holder fits into a hole in the stent. A ball-and-socket joint allows a user to adjust the guide by pivoting a bushing within the bushing holder. Harter thus allows for transfer of information from the model to the patient's mouth. This adjustment, however, has the same limitations of free-hand adjustment because a user adjusts the guide in 3D space with little control.
Moreover, the Harter guide limits a user's ability to make adjustments to pivot angle independent of translational movement. The pivot point of the joint is positioned well above the occlusal plane and at a distance from the jawbone. Adjustments to the pivot angle above the teeth results in significant translation of the point of entry of the drill bit at the jawbone below. As the guide pivots, therefore, a correction must be made to the translation. This adds to the difficulty of achieving accurate positioning.
There is a continuing need to reduce the costs and complexities associated with existing implant procedures. Conventional techniques generally require many steps to be performed by different people. Such additional steps create undesirable consequent increases in overall cost and overall procedure time.
In light of the forgoing, it would be beneficial to have a method and apparatus for aligning a dental implant which overcomes the above and other disadvantages of known implant positioning systems and methods. What is needed is an improved method and apparatus for controllably and quantifiably determining and adjusting a desired guide trajectory that would allow accurately and repeatably performing a dental implant osteotomy and placing of a laboratory analog of an implant.
What is needed is a simple and easy-to-use dental guide device and method. What is needed is a method for planning and positioning a dental implant with increased flexibility. What is needed is a method that allows for various processes to be performed at different times and locations. What is a needed is a method for reducing the time to perform implant planning and positioning.